locusta (fate)

Assassin-class Servant introduced in Fate/Grand Order. Nero Claudius' personal poisons expert and purportedly history's first serial killer. She was responsible for the assassinations of Nero's father Claudius at Agrippina the Younger's behest, and Claudius' son Britannicus, born from his third wife Valeria Messalina, at Nero's behest. Along with Nero's other 'favorites', Locusta was eventually executed for her crimes following Nero's suicide.